Variable speed gearing



Aug. 2, 1932. H. J. THOMSON 1,870,076

VARIABLE SPEED GEARING Filed June 5, 1929 4 Sheets-Sheet 1 Aug. 2, 1932.THOMSON 1,870,076

VARIABLE SPEED GEARING Filed June 5, 1929 4 Sheets-Sheet 2 Afar/lay.

2, 1932- H. J. THOMSON I VARIABLE SPEED GEARING Filed June 5, 1929 4Sheets-Sheet I5 J. THOMSON I VARIABLE SPEED GEARING 7' 4' Sheets-Sheet4- filed June 5, 1929 fivmwrae 7. EM 14/ 0 7 8 1A V Patented Aug. 2,1932 UNITED STATES;

HEIIEY J'EITBEYS THOMSON, E WOODFOBD GREEN, ENGLAND VARIABLE SPEEDGEABING Application filed June 5, 1929, Serial He. seems, and in GreatBritain June 20, 19,8.

This invention relates to electromechanical powe transmission systems inwhich power shaft, load shaft and a lay shaft are interconnected by athree-member epicyclic gear, and a dynamo-electric machine upon orgeared to the lay shaft supplying or supplied by a dynamo-electricmachine upon or geared to one of the other shafts affords a means ofvarying the torque transmitted to the load shaft by electrical controlof the dynamo-electric machines. It is not material to which members ofthe gear the power,

load and lay shafts are connected provided that if the load shaft isheld stationary the lay shaft rotates in the opposite direction to thepower shaft. k

The purpose of the invent1on is to extend the range of application ofsuch systems, to extend the torque range they are capable of giving, andto economize in the weight of the dynamo-electric machines employed.

To this end instead of mounting the electrical machines directly uponthe shafts interconnected by the epicyclic gear, or gearing 3 thempermanently to those shafts as has been done hitherto, this inventionprovides for the interposition of a variable speed ear between a dynamoand the correspon 'ng epicyclic gear shaft so that at one part of thecycle of control when the epicyclic gear shaft in question is rotatingslowly the dynamo is geared up from it to a high ratio, while in anotherpart of the cycle the gear ratio is made lower or the machine is lockeddirect to the shaft.

A further saving in res ct of the electrical machines is achieved yusing one for two purposes. To this end clutches are provided by whichone dynamo may be connected to the load shaft in one part'of the cycleand to the power shaft in another part. Preferably gearing is interposedbetween the machine and the load shaft of such ratio that when the layshaft is stationary the load shaft dynamo clutch member isrotating atthe speed of the power shaft clutch member. In this way the feature of avariable gear between a dynamo and its epicyclic gear shaft is combinedwith the notion of changing over the dynamo from one shaft to another.

A further means of extending the range of application and operationconsists in the intro uction of a second epicyclic gear having onemember driven by the power shaft, the lay shaft of the first gearforming the load shaft of the second.

Examples illustrative of the application of the invention are shown inthe accompanying drawings of which Figure 1 "is a simplified elevationhalf in section of a system shown diagrammatically in Figure 2. v

' Figures 3 to 13are diagrams corresponding with Figure 2 of othersystems.

Figure 14 is a diagram of electrical connections suitable for suchsystems.

In Figures 1 and 2 a motor 1 which may be an internal combustion orother engine or an electric motor drives a power shaft P which carries asun pinion s of an epicyclic gear 8, p, 2'. The planet pinion carrier ;0is upon a load shaft L. The outer sun wheel or internally toothed wheel2' is upon a memberrepresenting, and herein referred to as, an auxiliaryor lay shaft A. The load shaft is connected not only with the load, forinstance the wheels of a vehicle, but also through a variable gear 3with a dynamo-electric machine M. 'The lay shaft A is connected '80through variable gear 4 with a dynamo-electric machine G. Clutch Tserves to lock the gear s, p, a, solid. Brake B serves to hold the layshaft stationary. Clutch 5 enables dynamo M to be connected to the primemotor shaft when its driving connection through gear 3 with the loadshaft has been put out of action by the release of brake 6 whichnormally holds stationary the internally toothed wheel of gear 3. Sinceclutch 2 is engaged for all normal operations of the system savestarting the en inc and some methods of reversing, it will understoodthat connection to the prime motor shaft is also connection to the powershaft, except when star-tin or reversing is in question. A dog clutc 7serves to put the gear 4 out of action by connecting d namo direct tolay shaft A.

A pre erred scheme of control for this system is as follows. Clutch2being engaged and brake 6 applied dynamo G is driven. by the power shaftthrough gears z, p, s and 4. Current from this machine is fed to d namoM and electrically regulated in well own manner, for instance b shiftingthe brushes of the machines, (0. for instance patent of J. G. P. ThomasNo. 948,436 or No. 968,290). The load shaft turns when the torqueexerted upon it by M through gear 3 and by P throu h gear 8, p, z (owingto the resistance G) is suflicient to turn the load. By strengtheningthe field of G and weakening that of M the speed of G can be reduced toa small value when brake B may be applied and the power transmissionmade wholly mechanical. Dog clutch 7 may now be engaged with A. Brake 6is then released, clutch engaged, and brake B released. Machine M isthen driven direct by the prime motor shaft P and may be made to supplyelectrical power to the machine G which now runs as a motor direct couled to the lay shaft A. Upon the load shaft attaining the same speed asthe prime motor clutch T may be engaged and the whole power transmissionmade mechanical again.

For starting the engine, in case it is an internal combustion engine,the machine M may be driven from a battery as described hereinafter withreference to Figure 14 and clutch 5 engaged. A reverse drive may beobtained by engaging clutches 5 and T so that M is driven mechanicallyby the power shaft through 5 and can supply electrical power to G, whichdrives the load shaft di- {)ec tr or through gear 4, gear 8, p, i beinglocked In lieu of the epicyclic type of gear 3, or the 2-speed changegear 4 any other suitable gear may be employed for the purpose ofconnecting a dynamo-electric machine to a shaft. In Figure 3 chains andsprockets are shown. Machine M is connected either with the load shaftthrough sprockets and chain 8 and do clutch 9 or with the prime motorsha t through sprockets and chain 10 and clutch 5; as in Figures 1 and 2there is a change of gear ratio upon change over being effected by therelease of clutch 9 and engagement of clutch 5, but in this case themachine is geared to the power shaft and not directly coupled. Machine Gis connected with the lay shaft A either through sprockets and chain 11and dog clutch 12, or through sprockets and chain 13 and clutch 14. Thisarrangement may be used to give two reverse speeds according as clutch12 or 14 is engage and such speeds may be obtained either by engagingclutch T or by holding shaft P stationary by means of brake 20. Thedrive is electrical as above described with reference to Figure 2,machine M is driven as a generator by prime motor 1 through clutch 5.and supplies power to G which is transmitted through 11 and 12 or 13 and14 to A, and thence through the locked or operative gear s, p, z to L.

In Figure 4 the load shaft L is indicated as geared to an axle 15 of thevehicle wheels through bevel gear 16; the machine M is geared by bevelgear 17 and dog clutch 18 to another axle 19 of the vehicle; since thetwo axles are connected together through the wheels and the rails orroad on which the vehicleruns machine M is joined to shaft L when clutch18 is engaged and to the prime motor shaft when clutch 5 is engaged. Incase of a tractor vehicle pulling a train of vehicles, otherdynamo-electric machine corresponding with M may be connected with theaxles of the trailer vehicles, and supplied electrically like themachine M while the latter is connected with the load shaft. In this arrangement the engine may be started by the aid of machine G drivenelectrically, either by engaging clutch 14 and clutch T, orby engagingclutch 5 and employing machine M as before described.

In Figure 5 there is no gearing between the dynamo-electric machines andthe shafts of the epicyclic gear. The machine M may be connected eitherwith the load-shaft L by clutch 21 or with the prime motor shaft byclutch 5. If clutches 2, 5 and 21 are engaged simultaneously they havethe effect of clutch T in the preceding figures, that of locking solidthe gear a, p, z. A dog clutch 22 is engaged for reversing, for whichpurpose machine M is driven by the prime motor through clutch 5 andsupplies electrical power to the machine G. This scheme achieves all theadvantages of that described in the patent to Thomas No. 968,290 with asaving of one electrical machine.

It will have been observed that the systems described above, like thosealready known, aiford two speeds on which the power transmission can bewholly mechanical, one when the lay shaft is held stationary, the otherwhen the epicyclic gear is locked solid. In some cases it is convenientto arrange for additional mechanical speeds; as-thereby, for a giventotal range of speed variation, the range of a variable speed gearbetween the load shaft and the load, for instance between shaft L andthe wheels of a vehicle. The cycle of control above described is carriedthrough with more wheels are brought to a speed suitable for theengagement of the second gear; simultaneously with the engagement of thesecond gear the cycle of contro is recommenced; andso on.

An arrangement offering greater advantages is the employment of a secondepicyclic gear of the three-member type; thepower shaft drives onemember of each gear, another member of one gear drives the load shaft,another member of the other gear drives (or is driven by) the lay shaft,while the remaining members of the two gears are connected together.

One example of this arrangement is shown in Fi re 6, applied to a schemein which the electrical machine M -is permanently connected with theengine shaft, and not changed overduring the cycle from load shaft topower shaft as described with reference to igure 5. The additionalepicyclic gear is 81, 61, p1; its sun wheel 81 is joined to the powershaft P, its lanet pinion carrier 121 to the lay shaft A o the gear 8,12,11, while its internally toothed wheel i1 is joined to a lay shaft A1carrying the machine G; a brake B1 serves to hold this wheel stationarywhen required. In this scheme no use need be made of electrical controlfor low speeds; the first speed is obtained by applying brake B andengaging clutch 2; the power is transmitted who] y mechanically throughgear a, p, i; the second speed is obtained by applying brake B1 insteadof brake B; the ower is transmitted wholly mechanically t rough the gear81, pl, '51. For higher speeds both brakes are released and the machineG is supplied electrically from machine M. A top speed, on which thepower transmission is again wholly mechanical, is obtained by engagingclutch T1. A reverse mechanical drive may be obtained by applying brakeB and engaging clutch T1; or a reverse electrical drive may be obtainedby applying brake B and supplying machine G from machine M. The enginemay be started by supplying machine G from a battery and throwin inclutch T1.

The epicyclic gears so far escribed have been of the spur wheel type; itis equally possible to employ bevel wheel epicyclic gears. In Figure 7the auxiliary epicyclic gear 81, 721,711 is of this type. The machine Minstead of being ,on or connected with the load'shaft L as in Figures 1to 5, is upon the lay shaft A of the gear 8, 12,2 which forms the loadshaft for the gear 81, pl, 51. The cycle of control for this scheme isas follows. A low speed with mechanical power transmission is obtainedby applying brake B and engaging clutch 2. By releasing the brake andsuppl ing machine M electrically from machine the speed of L may beincreased and that of G diminished until it is nearly stationarywhereupon brake B1 may be applied and the electrical transmission ofpower eliminated. For higher speeds brake B1 is released and the machineG is supplied by the machine M, its speed being increased until itreaches that of the power shaft. Clutch T1 may then be engaged and theelectrical power transmission a ain eliminated. The engine may be starteand a reverse speed may be obtained mechanically or electrically, asdescribed with reference to Fig-' ure 6, save that for the electricalreverse machine M is driven from machine G instead of vice versa.

A modification of this scheme is shown in Figure 8. The change isconstructional only, the lay shaft A1 being made concentric with the layshaft A so that machine G is to the right of the gear 81, pl, '51, whilemachine M is to the left. The cycle of control is as above described;save that as clutch T1 now connects the prime motor 1 with the lay shaftA a reverse s eed cannot be obtained in the manner descri ed, and eitherthe prime motor must be made reversible or an ordinary reverse gearadded if reverse driving is required.

Fi re 9 is the same as Figure 8 save for the addition of a thirdelectrical machine M1 upon the prime motor shaft. This machine takes theplace of machine M for those speeds on which in Figure 8 machine Msupplies electrical power to machine G. A reverse speed can now be gotby engaging brake B and su plying electrical power from M1 to drive G inthe forward direction.

Figure 10 is a further modification of the arrangement of Figure 8, inwhich by thev addition of a clutch 21 provision is made, substantiallyas in Figure 5, for connecting machine M either to the load shaft of thegear 81, 21, 51, that is the lay shaft A, or to the prime motor. Theclutch marked T1 in Figure 8 is marked 5 in Figure 10 as in Figure 5,and as in the latter figure clutch 5 serves with the clutch 21. toperform the function of clutch T1 of Figure 8.v

In Figure 11 the epicyclic gear 81, pl, 121, is of the spur gear typeand a variable ear 4: is interposed between lay shaft A (0 gear 8, p, iwhich is the load shaft for gear 81, pl, 711) and machine M. A brake 24serves to make the gear operative. The lowest mechanical s eed isobtained as before by applying bra e B and engaging clutch 2. Then brakeB is released and brake 24 applied and machine M is suppliedelectrically from the G are ared to their respective epic clic gearshafts y sprockets and chains as in igure 3.

Figure 14 shows electrical connections suitable for the scheme of Figure12 and enerally speaking for all the schemes described so far as theycall for the integers shown. Machine M is indicated as controlled byshifting its brushes 25, 26, and machine G as controlled by a variaberesistance 27 shunting it field 28. The invention is not limited tothese methods of control. Aswitch 29 serves either to connect themachines in series or to join the battery 30 across machine M for thepurpose of driving M as a motor. A reversin switch 31 serves to reversethe field of G.

%o start the engine battery 30 is connected across machine M by switch29, M is speeded up by shifting its brushes forward from the maximumtorque position shownin full lines, and on a suitable speed beingreached clutch 5 is engaged; on the engine starting switch 29 andbrushes 25, 26 are returned to the position shown and clutch 5 isdisengaged. To start the vehicle clutches 9 and 12 are en aged and thenclutch 2 and brake B is gra ually applied; this gives a low speedmechanical drive. Speed can be increased by releasing brake B, andgradually introducing resist ance 27 into shunt with the field 28 ofmachine G; electrical power is then delivered to machine M. After theshunt resistance has been increased to maximum value, andv if desiredthe shunt circuit broken, brushes 25, 26 of machine M are moved forwardtowards the position shown in dotted lines; by this means machine G isbrought nearly to a standstill and brake B1 can then be engaged to givea second mechanical speed. For fur-.

ther increase of speed clutch 12 is disengaged and clutch 14 (of whichboth parts are stationary) and clutch 5 (of which both parts arerotating at engine speed) are engaged, and clutch 9 is disengaged.Brushes 25, 26 are then'moved further forward causing machine M togenerate current, and when the current is sufficient to resist thebackward torque on G brake B1 is released and G is driven forwardelectrically. Continued movement of brushes 25, 26 ultimately brings allthe members of both gears s, p, z',and

81, 121, 2'1, to engine speed, when clutch T1 is engaged and the driveis again mechanical, brushes 25, 26 being moved backward until thedelivery of current to G ceases. If desired clutches 5 and 14 may bereleased and machines M and G brought to rest. A reverse speed isobtained by engaging clutches 5 and T1, and throwing over switch 31.Machine M is driven as a generator through gearing 10, and suppliespower electrically to the reversed machine G which may drive througheither gear 11 or gear 13, clutch T1 locking the epicyclic gears.

A different modification of Figure? iS shown in Figure 13 where themachine M instead of being connected to the joined members of the twoears, i. e. to shaft A which is the lay shaft or gear a, p, z, and theload shaft for gear 81, pl, 011, is oined to the load shaft L. Provisionma be made if desired for disconnecting machine M from-the load shaft Land connecting it to the prime motor shaft as explained with referenceto (for instance) Figure 4 or 5. In the construction of Figure 13 thegears 8, 12,1, and 81, p1, i1, are brought together and can convenientlybe built in one gear box.

The constructions illustrated are exam les only; it should be clear fromthem how urther modifications may be made by employing in the scheme ofone figure features illustrated in aonther figure; for instance it willbe apparent that the gear .9 p, z' of any figure ma be replaced b thecombined gears 8, 12,2 an 81, pl, 21 of igure 6, 2'1 being joined to thelay shaft A and s and 31' to the power shaft; or the juxtaposedarrangement of gears s, p, i, and 81, p1, 2'1, shown in Figure 13 may beemployed in Figure 7 by extending shaft A to the right as a sleevearound the load shaft.

I claim 1. In an electromechanical power transmission system thecombination of power, load, and lay shafts, an epicyclic gearingconnecting said shafts, a dynamo-electric machine connected with one ofsaid shafts, a second dynamo-electric machine, two driving connectionsof different speed ratio for connecting said second dynamo-electricmachine to one of the other shafts, means for rendering either of saidconnections operative, electri-' cal connections between said dynamoelectric tric machine connected with the lay shaft, a

second dynamo-electric machine, means for connecting said seconddynamo-electric machine to the load shaft, other means for connectingsaid second dynamo-electric machine to the power shaft, electricalconnections between said dvnamo electric machines, and electricalcontrol means for causing said machines to supply current the one to theother.

3. In an electromechanical power transmission system, the combination ofower, load, and lay shafts, an epicyclic gearing interconnecting saidshafts, a dynamo-electric machine connected with the lay shaft, a seconddynamo-electric machine, means including a clutch for connecting saidsecond dynamo-electric machine to the power shaft, means connecting saidsecond dynamo-electric machine to the load shaft of such speed ratiothat when the lay shaft is stationary both parts of said clutchare'rotatin at the same speed,'electrical connections etween said dynamoelectric machines, and electrical control means for causing saidmachines to supply current the one tothe other.

a. In an electromechanical power transmission system, the combination oftwo threemember epicyclic gears, a power shaft, means connecting saidpower shaft with one member of each gear, means connecting anothermember of the one gear with one member of the other gear, a load shaftconnected with the remaining member of the one gear, a la shaftconnected with the remaining mem er of the other gear, a dynamo-electricmachine connected with said lay shaft. a second dynamo electric machineconnected with another member of said gears, electrical connectionsbetween said dynamo electric machines, and electrical controlling meansfor causing said machines to supply current the one to the other.

5. In an electromechanical power transmission system, the combination oftwo threemember epicyclie gears, a power shaft, means connecting saidpower shaft with one member of each gear, means connecting anothermember of the one gear with one member of the other gear, a load shaftconnected with the remaining member of the one gear, a lay shaftconnected with the remaining member of the other gear, a dynamo-electricmachine connected with said lay shaft, a second dynamo-electric machineconnected with another member of one of said gears, electrical.connections between said dynamo electric machines, and electricalcontrol means for causing said machines to supply current the one to theother.

6. In an electromechanical power transmission system, the combination oftwo threemember epicyclic gears, a power shaft, means connecting saidpower shaft to one member of each gear, a lay shaft connected withanother member of one gear, a dynamo-electric machine connected to saidlay shaft, a second dynamo-electric machine, means for connecting saidsecond dynamo-electric machine to the power shaft, means for connectingsaid second dynamo-electric machine to one of the remaining members ofsaid gears, means connecting together two of saidremaining members oneofeach gear, a load shaft connected 530 the other of said remainingmembers, electrical connections between said dynamo electric machines,and electrical control means for causing said machines to supply currentthe one to the other.

7 In an electronechanical power transmission system, the combination ofpower, load and lay shafts, an epicyclic gearing interconnecting saidshafts, a dynamo-electric machine, variable gearing connecting saiddynamo-electric machine to the lay shaft, a second dynamo-electricmachine connected to one of the remainin shafts, electrical con nectionsbetween sai dynamo electric machines, and electrical'control means forcausing said machines to supply current the one to the other.

8. In an electromechanical power transthe other gear, electricalconnections between said dynamo electric machines, and electricalcontrol means for causing said machines to supply current the one to theother.

9. In an electromechanical power transmission system, the combination oftwo threemember epicyclic gears, a power shaft driving one member ofeach of said gears, a lay shaft connected to another member of one gear,a load shaft connected to another member of the other gear, means oiningtogether the remaining members of the two gears, two dynamo-electricmachines, one connected to one member of one of said gears, means forconnecting the other to another member of that gear, electricalconnections between said dynamo electric machines, and electricalcontrol means for causing said machines to supply current the one to theother.

10. In an electromechanical power transmission system, the combinationof two threemember epicyclic gears, a power shaft driving one member ofeach of said ears, a lay shaft connected to another mem er of one gear,a load shaft connected to another member of the other gear, meansjoining together the remaining members of the two gears, twodynamo-electric machines, one connected to one member of one of saidgears, means for connecting the other to another member of that gear,and means for holding stationary the member of one gear not connectedwith the power shaft or load shaft, means for holding stationary themember of the other gear connected with the lay shaft, electricalconnections between said dynamo electric machines, and electricalcontrol means for causing said machines to supply current the one to theother.

11. In an electromechanical power transmission system, the combinationof two three member-epicyclic gears, a power shaft driving one member ofeach of said gears, a load shaft connected to another member of one ofsaid gears, a lay shaft connected to another member of the other gear,means joining together the remaining members of said gears, adynamo-electric machine connected with said lay shaft, a seconddynamo-electric machine, means for connecting said seconddyname-electric machine to the joined members of said gears, means forconnectin said second dynamo-electric machine to t e powersheft,electrical connections between said dynamo electric machines, andelectrical control means for causing said machines to suppl current theone to the other.

in testimony whereof I have signed name to this specification. I

HEDLEY JEFFREYS THOMSON;

